I've used Word professionally since the mid-1990s. I do know how to use it properly, and it still sucks.
"Writing" isn't meant to be done in a word processor, which was developed as a business tool, not a creative tool. Writing should be done in whatever tool one wants to write in.
Word is, be design, both a desktop publishing app and a secretarial tool. For book-length writing, it works poorly with long files, the file format is subject to corruption. The docx format is also proprietary and subject to Microsoft's whim; any conversion scheme is a hack (though Pandoc and many others do work adequately). Unless you learn the ins and outs of Word's style scheme (and sometimes even if you do) and follow it slavishly, formatting is often inconsistent and there's no certainty that the styles you apply to make your document to make it look a certain way ensure it looks that way on someone else's machine.
There's no doubt, though, that a Word-compatible word processor needs to be in every writers' toolkit, since it is the standard in the publishing world.
[0] https://www.sfwriter.com/wordstar.htm, scroll down or search for THE LONG-HAND PAGE METAPHOR.